1. Field of the Invention
The invention relates to a vehicle steering apparatus provided with a lock mechanism.
2. Description of the Related Art
From Japanese Patent Laid-Open Publication No. 2001-48032 a vehicle steering apparatus having a lock mechanism is known. This apparatus is also provided with a variable gear ratio mechanism disposed midway in a steering shaft coupled to a steering wheel, which enables the ratio of an amount the steering wheel is turned to an amount steered wheels are turned to be changed. The lock mechanism restricts relative rotation of an input shaft and an output shaft of the variable gear ratio mechanism. This lock mechanism includes a lock holder provided on a rotor side of a motor housed within the variable gear ratio mechanism and a lock arm provided on a stator side of the motor. The lock mechanism locks by engaging the lock arm with an indented portion formed in the surface around the circumference of the lock holder.
This apparatus, however, may be unable to lock if the opening width of the indented portion of the lock holder is narrow. For example, when the apparatus attempts to lock when the motor is rotating, a locked state may be difficult to achieve if the indented portion of the lock holder is not provided at the engaging position of the lock arm.
It is conceivable that this problem can be solved by making the opening width of the indented portion wide. Widening the indented portion of the lock holder, however, results in an increased degree of play between the lock holder and the lock arm when they are in a locked state. As a result, the positional relationship between the lock holder and the lock arm is unable to be accurately detected such that appropriate steering control is unable to be performed.